Summary Hli-Inter Inc. AS 350 BA, registration C-FPOO, serial number2508, with one pilot and two aircraft maintenance engineers (AMEs) on board, was making a series of flights to adjust rotor blade alignment and autorotation rpm. On the second autorotation of the flight, the collective lever locking plate accidentally engaged without the pilot's knowledge and locked the flight control against the low stop. About 800feet above ground level (agl), the pilot tried to arrest the descent and pulled on the locked collective lever, but he could not free it. The aircraft continued its descent and, after the flare, landed hard. The pilot was uninjured and the AMEs sustained minor injuries. The aircraft did not catch fire but sustained substantial damage. The time of the occurrence was 1348 eastern standard time. Ce rapport est galement disponible en franais. Other Factual Information History of the Flight Three days before the occurrence, the pilot and the company check pilot did several practice autorotations. They noted that autorotation rpm was 60rpm slower than the speed specified for the aircraft weight at the chosen altitude. On the day of the occurrence, an aircraft maintenance engineer (AME) working for Hli Technik Inc., an approved maintenance organisation (AMO), backed off the collective low stop screw six turns to raise autorotation rpm. He also had to remove, adjust, and reinstall the collective lock located on the floor. The pilot and one AME then made three flights to adjust main rotor blade alignment. Those flights were without incident. The fourth flight, which was the occurrence flight, was to check the rotor rpm on autorotation. The pilot and two AMEs were on board the helicopter. At 1200feet above ground level (agl), the pilot performed an autorotation with the collective against the low stop at a speed of 80mph. On this check, he reduced drive power to idle. Rotor speed was 365rpm. After increasing power, the pilot noticed a small amount of friction in the collective movement. He checked lever travel by raising and lowering it a few times. Noting that the control was moving normally, the pilot climbed to 1400feetagl, where he initiated a second autorotation. The autorotation was normal down to 800feetagl. After re-applying power, the pilot noticed that the collective locking plate was engaged and was impeding lever movement. The pilot tried unsuccessfully to disengage the locking plate with his thumb. About 40 feet above ground, the pilot executed a flare and landed on Runway36 at a speed of about 20mph. After the initial touchdown, the aircraft bounced and fell hard on its belly. The tail rotor drive shaft was severed on the second impact, and the helicopter started to spin about its main rotor mast until an AME closed the throttle; the pilot was concerned that the collective would be released suddenly and cause the aircraft to lift off, so he used his left hand to hold the lever down rather than cut power. The helicopter came to rest and the pilot finished shutting down all systems before evacuating the aircraft. When the aircraft came to rest, the pilot could not notify Val-d'Or radio because the radio was out of order. The emergency locator transmitter (ELT) activated at 13481. The airport security officer arrived at the occurrence site at 1350:50. Rescue1 arrived at the site at 1356. An ambulance arrived at the emergency control centre at 1405, and was directed to the site 17minutes after the crash. The Pilot The pilot was certified and qualified for the flight in accordance with existing regulations. He had about 4500flying hours on helicopters, including about 900hours onAS350. Helicopter Flight Manual Section 4.1 of the AS 350 BA Flight Manual requires that the friction setting on the cyclic and collective levers be adjusted on the pre-flight check so as to prevent the levers from moving without pilot input during flight. During the pre-flight check, the pilot unlocked the collective control to adjust the friction setting, and could have noticed whether the locking tab interfered with the collective control. Since the main rotor rpm was less than the speed published by the manufacturer, the pilot had to do autorotation checks. The correct range for autorotation rotor speed was 395-415rpm. The target rpm would depend on the altitude and weight of the aircraft. The procedure followed by the pilot, which was to reduce power when checking autorotation rpm, was different from the procedure published in the aircraft flight manual. First, the check should have been done at full power; and second, in the case of an engine-out drill, the fuel flow control should not have been returned to full power, while monitoring the T4temperature, until the autorotation was completed and the aircraft was on the ground. The pilot followed the procedure he was taught during autorotation training on that type of helicopter. The Helicopter Eurocopter AS 350 BA, registration C-FPOO, serial number2508, type certificateH83, had been repaired using structural/fuselage parts from a damaged AS350Daircraft, serial number1131. Hli-Expert, who owned the two damaged helicopters, had obtained permission from Transport Canada to have the C-FPOO repaired and converted into an AS350BA. Hli Fix Services Inc., an approved maintenance organization (AMO), completed the project in one stage up to maintenance release. Eurocopter had issued Service Bulletin (SB)01-00-035 Conversion AS350B Helicopter into AS350BA Version. But this SB was effective only if the AS350B was airworthy at the time of conversion. Transport Canada approved the conversion without regard to the effectivity limitation prescribed by Eurocopter. The project included 14supplemental type certifications, including a powerplant change. Examination of the occurrence helicopter and its records indicate that modification350A07-1995 (blanking of upper cavity in collective pitch lever stop), deriving from SB01-00-035, was not completed. Moreover, modification350A07-0679, which consisted of replacing the normal collective lever with a collective lever with a control box mounted at the end, was only partly completed; the collective lever low-pitch stop adjusting screw had not been inverted. Upon receipt of a signed application for a Certificate of Airworthiness attesting that all applicable airworthiness requirements had been complied with and that the aircraft conformed to its type design, Transport Canada completed an inspection of the converted aircraft and issued a Certificate of Airworthiness on 08June2001. The helicopter had accumulated about 300hours at the time of the occurrence. Damage to the Helicopter When examining the occurrence helicopter before it was moved, an AME noted and reported that the collective lever locking plate was not engaged and, after engagement, it disengaged normally with light pressure on the collective lever; these observations were corroborated by the TSB investigator. But the space between the end of the collective lever and the electrical console was about 5mm (seePhoto1), which is 11mm less than the Eurocopter specification (16mm0.5mm) (seePhoto2). Witness statements indicated that the space between the electrical console and the end of the collective lever was greater than was observed after the occurrence, and the locking plate did not interfere with collective lever travel. Autorotation rotor rpm is set by adjusting the pitch links and rotor control links. Based on the rigging tool specified by Eurocopter, it was established that the adjustment of the pitch change links from the blades to the swash plate and the control links from the input rods to the servo-controls exceeded the manufacturer's dimensions by 5mm and 8.9mm, respectively. Consequently, the collective lever was lower than it should have been for a given blade pitch, resulting in low rotor rpm on autorotation. Photo1. Space for locking plate: 5mm Photo2. Normal position with space of 16mm The Approved Maintenance Organization Hli Fix Services Inc. held an approved maintenance organization (AMO) certificate and was incorporated on 22March2000. The AMO was managed and operated by its president, who was also director of maintenance and an AME. He also provided a helicopter importing and rebuilding service. For the previous 12years, he had held an aircraft maintenance engineer licence for rotary-wing aircraft, which was valid for the AS350, EC120, B206 and R22. He was also director of maintenance for three air operators and maintained their aircraft.